The present invention relates to an alarm apparatus for detecting an environmental abnormality such as a fire or gas leakage and, more particularly, to an audio signal generator of an alarm apparatus.
For example, Japanese Patent Disclosures (Kokai) Nos. 54-5698 and 52-29199 disclose systems in which an audio signal generator is provided for each of a plurality of sensors in fire alarm equipment. In either of the above systems, a tone converter such as a loudspeaker is provided for each sensor so that the sensor generates an alarm sound upon operation. Therefore, an "ON" sensor can be easily discriminated from "OFF" sensors.
However, according to the above conventional systems, if the system is installed in a building such as a hotel having a large number of private rooms, only a person in a room where a sensor is operated, and maintenance personnel in a control room where a receiver is installed, will be informed of an alarm state. Therefore, escape of others may be delayed upon occurrence of a fire or the like.
In some systems, special lines extend from the receiver to, e.g., alarm bells provided in common places such as hallways so that the alarm bells generate alarm sounds in synchronism with the activated sensor. However, since sound insulation of buildings has recently been improved, people inside the rooms often do not notice the alarm sounds. On the other hand, if the alarm sound is increased louder than necessary, people may be confused and cause a panic when a false alarm is generated.